The broadcast spectrum is divided up into different frequencies and allocated among different broadcasters for various uses in different geographic regions. The frequencies of the spectrum are allocated based on licenses granted to the broadcasters. Based on the allocations, a broadcaster may be limited to broadcasting a specific type of content, such a television signal, on a certain frequency within a certain geographic radius. Broadcasting outside of an allocated spectrum could be a violation for the broadcaster.
If a broadcaster wishes to transmit another type of content within that geographic radius, the broadcaster may be required to obtain an additional spectrum license and in turn be allocated an additional frequency within that frequency. Similarly, if a broadcaster wishes to transmit content within another geographic radius, the broadcaster may be required to obtain an additional spectrum license for that region. Obtaining additional spectrum licenses, however, may be difficult, time consuming, expensive, and impractical.
In addition, a broadcaster may not always fully utilize an entire portion of spectrum for which it has been granted a license. This may create inefficiencies in the utilization of the broadcast spectrum.
Moreover, the anticipated use of the broadcast spectrum may be changing. For example, current broadcast television solutions are monolithic and designed for a primary singular service. However, broadcasters may anticipate providing multiple wireless-based types of content, in addition to broadcast television in the future, including mobile broadcasting and IoT services. In particular, there are many scenarios where a large number of devices may all wish to receive identical data from a common source beyond broadcast television. One such example is mobile communication services, where a large number of mobile communication devices in various geographic locations may all need to receive a common broadcast signal conveying the same content, such as a software update or an emergency alert, for example. In such scenarios, it is significantly more efficient to broadcast or multicast the data to such devices rather than individually signaling the same data to each device. Thus, a hybrid solution may be desirable.
To more efficiently utilize the broadcast spectrum, different types of content may be time-multiplexed together within a single RF channel. Further, different sets of transmitted content may need to be transmitted with different encoding and transmission parameters, either simultaneously, in a time division-multiplexed fashion (TDM), in a frequency division-multiplexed (FDM), layer division-multiplexed (LDM) or a combination. The amount of content to be transmitted may vary with time and/or frequency.
In addition, content with different quality levels (e.g. high definition video, standard definition video, etc.) may need to be transmitted to different groups of devices with different propagation channel characteristics and different receiving environments. In other scenarios, it may be desirable to transmit device-specific data to a particular device, and the parameters used to encode and transmit that data may depend upon the device's location and/or propagation channel conditions.
At the same time, the demand for high-speed wireless data continues to increase, and it is desirable to make the most efficient use possible of the available wireless resources (such as a certain portion of the wireless spectrum) on a potentially time-varying basis.